Bridging plug



Feb. 27, 1940. w. T. WELLS BRIDGING PLUG Filed July 15, 1939 /N VENTOR Wam-El? Z" WELLS B Y @C QM A TTORNE Y Patented Feb. 21, 1940 UNITED nSTATES BRIDGING PLUG Walter T. Wells, Glendale, Calif., assignor to Lane-Wells Company, Los Angeles, Calif., a corporation of Delaware Application July15, 1939, Serial No. 284,650

10 Claims.

My invention relates to bridging plugs, that is, to devices which are adapted to be lowered into a well casing and set at some intermediate point for the purpose of plugging or sealing off that portion of the casing below the bridging plug. Among the objects of my invention are:

First, to provide a bridging plug wherein slips or other frictionally operated wedge means are eliminated and the bridging plug is secured in its place by thermite welding;

Second, to provide a bridging plug which, although intended as a permanent seal or plug, is capable of being drilled up in the event it is desired to remove the plug;

Third, to provide a bridging plug which is particularly adapted to be lowered on an electric cable, thereby eliminating the time' and expense necessitated by the use of tubing string now commonly used to lower bridging plugs or equivalent devices;

y Fourth, to provide a bridging plug which utilizes the thermite-welded connection with the casing primarily as a, means of locking the bridgingv plug in place, but may, in addition., form a continuous weld to effect a sealing connection;

Fifth, to provide a bridging plug of this charf acter which may incorporate an auxiliary yieldable sealing gland adapted to be set after the plug is welded in place, so that a minimum quantity of thermite need to be used; that is,only

suillcient thermite need be used to effect a mey chanical connection with the casing, as distinguished from a sealed connection therewith; and

Sixth, to provide a bridging plug which is particularly simple and economical of manufacture and operation, and particularly emcient in its action. y

With the above and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawing, in which:

Figure 1 is an elevational view of my bridging plug as it appears when suspended from a conductor cable;

Figure 2 is an enlarged longitudinal sectional view thereof through 2-2 of Figure 1, showing the parts of the bridging plug in the positions assumed when running into the well casing and before being set;

Figure 3 is a longitudinalsectional view similar to Figure 2, but showing the bridging plug after it has been seated and welded to the well casing;

Figure 4 is a transverse sectional view through 4-4 of Figure 2, showing the thermite welding material before operation;

Figure 5 is a view similar to Figure 4, showing a modied form or arrangement of the thermite material in which individual pockets of thermite material are provided in place of a continuous ring; and

- for the thermite.

the thermite be packed in fairly solid so that Figure 6 is a transverse sectional view through 6 6 of Figure 3, showing one of the split rings which coact with wickers to prevent release of the packing element after the packing element is once set.

.My bridging plug includes a body member I of cylindrical form having an annular channel 2 provided'in its outer surface. The channel 2 is adapted to receive a non-explosive exothermic mixture 3 such as thermite. The thermite mixture may be held in place by a thin shell 4 which, if desired, may be soldered or otherwise connected with the body to form a sealed enclosure It is intended, however, that the shell 4 is supported against external hydrostatic pressure, but readily burns through and is destroyed when the thermite mixture is ignited.

The body I is provided -with a longitudinal bore which receives a stem 6. A shear pin 1 initially secures the stem to the body member. The stem 6 projects above the body member and is connected by means of a second shear pin 9 to an end iitting 8.

The end tting B is cup-Shaped and internally threaded at its upper end for connection to a cable head I0. The cable head in turn is secured to the lower end of a cable I I, which cable includes a conductor. The terminal I2 provided in the lower end of the cable head is connected with the conductor of the cable.

The terminal I2 is engaged by a contact element I3 mounted Within the end tting 8. A lead wire I4 is joined -to the contact element I3 and extends downwardly through a sealing plug I5 provided in the end fitting 8 and through a second sealing plug I6 which is screw-fitted into the body I. The sealing plug I6 extends to the channel 2 and is provided at its lower end with a suitable ignition element I 1 adapted, when the circuit thereto is completed, to ignite the thermite mixture contained in the channel 2. In order to facilitate distribution of flame around the entire circumference ofthe body I, a magnesium ribbon I8 may be provided in the thermite mixture in close proximity to the'ignition element and wrapped in a circle within the'channel 2, as shown in Figure 4. n

The lower end of the body I is reduced in diameter to form a mandrel I9, upon which iits a packing sleeve formed of rubber or analogous material capable of being expanded into contact with the walls of a surrounding casing. The end of the mandrel I9 receives a cup-shaped cap member 2I and the stem 6 extends downwardly through the cap member and is provided with a head 22 so that the cap member is supported by the stem 6.

The mandrel I9 is provided with wickers 23 which are adapted to be engaged by locking rings 24 carried in channels provided Within the cap member 2 I. The locking rings 26 are split so that they may expand over and contract into the wickers, and are so arranged that the cap member may move upwardly on the mandrel i9 for the purpose of expanding the packing sleeve, but

lock against downward movement of the cap member with respect to the mandrel, so that the packing sleeve when once expanded is prevented from returning to its initial position. In order to prevent leakage of uid around the stem 6, a packing element 25 is provided in the lower end of the mandrel I9.

Operation of my bridging plug is as follows: The bridging plug is lowered to the desired position within a casing (designated C in Figure 3). whereupon the circuit to the ignition element Il is completed, such circuit including a source of electrical energy and a switch located at the surface, but not shown. The thermite mixture, upon being ignited, generates a high temperature, melts the shell and liows outwardly into contact with the surrounding casing. The liquid in which the bridging plug is immersed tends to prevent undue flowing of the thermite mixture down the sides of the body member so that the burning material is maintained somewhat localized and readily bridges over and fuses to the surrounding casing, leaving a residue which is welded to the body and the casing.

By proper proportioning of the thermite mixture it is possible for the residue o f this mixture to form a complete seal between the bridging plug and the surrounding casing, but in the event a, less amount is preferred, which will merely Weld or secure the body in place, the packing sleeve 2D may be utilized. Thus, after the thermite mixture has completed its reaction and the residue 26 has locked the bridging plug to the casing, an upward pull on the cable first shears the pin 1 so that the head pulls upwardly on the stem and thereby pulls upwardly on the cap member 2| to expand the packing sleeve into the position shown in Figure 3. After a predetermined additional strain has been applied, calculated to properly seat the packing sleeve, the shear pin 9 severs and the cable head, together with its end tting 8, may be withdrawn from the well.

Inasmuch as it is not necessary for the thermite mixture to form a sealing connection with the casing, but merely to lock the bridging plug in place, it follows that in place of channels 2 the body member i may be provided with pockets 3|, as shown in Figure 5, which may have their individual ignition elements (not shown).

In order to insure movement of the stem 6.

even though the-body i may be materially heated, the body I, except at its upper and lower end, is.

substantially relieved from the stem so as to form an air space therearound.

Various changes and alternate arrangements may be made within the scope of the appended claims, in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

-1. In an oil well device: a body member adapted to be lowered into a well bore; a metallic exothermic reacting material carried by said body member and' adapted to now therefrom into con- .nection therebetween; and vmeans 2. A method of securing an object within a well casing, characterized by lowering saidobject and ,an exothermic reacting welding material as a unit to the desired location within the casing and thereupon igniting said material to release thermal energy calculated to weld said object tosaid casing.

3. An apparatus for securing an object within a well casing, comprising: a quantity of thermite carried by said object and adapted, when ignited, to now therefrom into contact with said casing, whereby, upon subsequent cooling of the thermite, a metallic bond is formed between said object and the casing.

4. A method of bridging a well casing, characterized by lowering into said casing an exothermic reacting material having a metallic residue, igniting said material whereby the residue of said material is caused to fuse to said casing.

5. A bridging plug for cased oil wells, comprising: a body member; exothermic reacting material for welding said: body member to a surrounding casing; means for igniting' said ma- 1 terial; and a packing element adapted to seal and a surrounding casing; and means for igniting said material. l

8. A means for securing a well tool within a well casing, comprising: a predetermined charge of exothermic reacting mixture adapted to be lowered with said tool and adapted to form a molten metallic residue capable of welding to a partvof said tool and a surrounding casing, said charge being positioned relative to said part so that upon` being ignited the residue bridges between said part and casing to form a welded confor igniting said charge.

9. A bridging plug for cased wells adapted to be lowered on a conductor cable and comprising: a fitting secured to said cable; a body member; a severable link between said body member and tting; an exothermic reacting welding charge carried by said body member, adapted, when ignited, to ow into contact with a surrounding casing and form a welded connection between the body member and casing; and means electrically associated with said cable for igniting said charge.

10. A bridging plug, as set forth in claim 9, wherein a packing means is carried by said body member, said packing means being operatively associated with said link to pack between said body member and the surrounding casing upon movement of said tting relative to said body member. i

WALTER T. WELLS. 

